• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.54-65
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• 2007

Parameter optimization technique is applied to planning UAVs(Unmanned Aerial Vehicles) path under artificial enemy radar threats. The ground enemy radar threats are characterized in terms of RCS(Radar Cross Section) parameter which is a measure of exposure to the radar threats. Mathematical model of the RCS parameter is constructed by a simple mathematical function in the three-dimensional space. The RCS model is directly linked to the UAVs attitude angles in generating a desired trajectory by reducing the RCS parameter. The RCS parameter is explicitly included in a performance index for optimization. The resultant UAVs trajectory satisfies geometrical boundary conditions while minimizing a weighted combination of the flight time and the measure of ground radar threat expressed in RCS.

• Journal of Astronomy and Space Sciences
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• v.30 no.1
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• pp.11-15
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• 2013

A collision-free formation reconfiguration trajectory subject to the linearized Hill's dynamics of relative motion is analytically developed by extending an algorithm for gravity-free space. Based on the initial solution without collision avoidance constraints, the final solution to minimize the designated performance index and avoid collision is found, based on a gradient method. Simple simulations confirm that satellites reconfigure their positions along the safe trajectories, while trying to spend minimum energies. The algorithm is applicable to wide range of formation flying under the Hill's dynamics.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.451-462
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• 2005

Optimal Trajectory Correction Maneuver (TCM) design algorithm has been developed using the B-plane targeting method for future Korean Mars missions. For every-mission phase, trajectory informations can also be obtained using this developed algorithms which are essential to design optimal TCM strategy. The information were computed under minimum requiring perturbations to design Mars missions. Spacecraft can not be reached at designed aim point because of unexpected trajectory errors, caused by many perturbations and errors due to operating impulsive maneuvers during the cruising phase of missions. To maintain spacecraft's appropriate trajectory and deliver it to the designed aim point, B-plane targeting techniques are needed. A software NPSOL is used to solve this optimization problem, with the performance index of minimizing total amount of TCM's magnitude. And also executing time of maneuvers on be controlled for the user defined maneuver number $(1\~5)$ of TCMs. The constraints, the Mars arrival B-plane boundary conditions, are formulated for the problem. Results of this work show the ability to design and analyze overall Mars missions, from the Earth launch phase to Mars arrival phase including capture orbit status for future Korean Mars missions

• Environmental and Resource Economics Review
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• v.21 no.3
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• pp.683-716
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• 2012

As the global concerns focus on the sustainable growth, the green growth has been one of key words for the Korean government's policy trajectory. This study measures the green index for OECD countries in order to gauge and diagnose the current status of the green growth policy for Korea. The empirical results tell us that Korea's green index is relatively small and it needs to benchmark UK for improving her green policy. The contributions of the current study are to use a large set of data for green growth and to result in quantitative empirical results.

• Journal of Oral Medicine and Pain
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• v.22 no.2
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• pp.295-307
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• 1997

This study was performed to investigate the reproductibility of eccentric mandibular movements according to preferred chewing side, range of mouth opening, type of lateral guidance and involvement of temporomandibular disorders. 50 patients with temporomandibular disorders and 65 dental students without any signs and symptoms were randomly selected for this study as the patients group and the control group, respectively. For recording and observation of eccentric mandibular movement trajectory, BioEGN$^\textregistered$ of Biopak$^\textregistered$ system (Bioresearch Inc., USA) was used. Each eccentric movement to anterior, right and left side was performed three times similar to the movement pattern for Pantronic Reproducibility Index. mandibular path was analyzed by three dimensional positional change and the three paths from one direction were compared with one another. From this, reproducibility index of one-directional lateral movement could be calculated, and total reproducibility index, named BioEGN reproducibility index(BERI), was also computed from three-directional eccentric movement likewise. BioEGN reproducibility Index could have four value of score by small or large scale, and by outgoing or incoming movement. The data were analyzed by SAS/stat program and the results obtained were as follows: 1. Right side chewing subjects showed more consistent pattern In reproducibility index in comparison between patients group and control group than left chewing subjects have done, and reproducibility was low in patients group. However, there was no difference between the two stoups in bilateral chewing subjects. 2. There were no difference in reproducibility index between preferred chewing side and contralateral side in unilateral chewing subjects whereas reproducibility index in left side on outgoing movement were higher than in right side in bilateral chewing subjects. 3. Difference in total reproducibility index(BERI) between canine guidance group and non-canine guidance group were not observed though difference in reproducibility index on lateral movement were observed in part. 4. There were no difference in reproducibility index between affected side and contralateral side in unilaterally affected patients, and between unilaterally affected patients and bilaterally affected patients in patients group. 5. Highly significant positive correlationship were shown among the four 쇼pes of total reproducibility index(BERI) in total subjects, and range of clinical mouth opening was negatively correlated with BEBI on outgoing movements and with index on outgoing movement to preferred side.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.43-44
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• 2002

중국 서북건조 사막지역에서 봄철에 기온이 올라가면서 강한 한랭전선을 동반한 저기압이 발달할 때 그 전선 후면에 미세한 모래먼지가 바람에 휘감겨 올라가 황사가 발생한다. 발원지에서 생성된 황사는 약 30%가 발원지에서 재 침적되고, 20%는 주변지역으로 수송되며, 50%는 편서풍을 타고 1,500-2,000km이상의 거리를 이동하여 우리나라, 일본 및 하와이에까지 침적되는 것으로 알려져 있다. (중략)

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.231-233
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• 1999

시공간 상에서 움직이는 물체의 이동경로는 일반적으로 MBR이 매우 크므로, R-tree 계열의 다차원 인덱싱 기법을 적용할 때 질의시 겹침 영역이 많이 발생하는 문제점이 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 time slice에 따라 이동경로의 MBR을 나누어 별도의 인덱스에 저장하는 기법을 제안한다. 이 기법을 적용하면 MBR의 평균 크기가 줄어들어 인덱스 페이지 및 데이터 페이지 접근횟수를 감소시킬 수 있을 뿐만 아니라, 시간이 지나 질의가 매우 드물게 수행되는 데이터에 대한 엔트리를 삭제하여 검색 범위를 줄이는 것이 용이하다. 또한 본 논문에서는 질의 성능을 최적화하기 위해서 time slice를 어떻게 설계해야 하는지에 대해서도 논의한다.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.289-303
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• 1991

The purpose of this study is to investigate the correlationship between Pantographic Reproducibility Index(PRI) scores and patterns of mandibular movements by mandibular kinesiograph(MKG) that has been used to diagnose temporomandibular disorders. PRI scores have been measured in normal and symptom groups by tracing Denar mechanical pantograph. Maximum lateral deviation, opening & closing velocity, and clinical rest position of mandibular movements have been analyzed in the same group when the mandible is opened and closed. According to to Helkimo's Dysfunction Index, the students and graduates of College of Dentistry are classified as 6 normal groups and 42 symptom groups. The obtained reslts are as follows : 1. The mean of PRI scores was larger in symptom groups than in normal groups. 2. The mean of maximal laterotrusion in frontal trajectory was larger in symptom groups than in normal groups. 3. There was little significant correlationship observed between PRI scores and patterns of mandibular movements by MKG.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.740-745
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• 2005

This study is intended to build a controller of redundant manipulators with the simultaneous abilities of trajectory tracking and obstacle avoidance without any preparations of path planning to achieve full automation even for one production of one kind, while keeping the avoidance ability high and keeping its shape away from object to reduce the possibility that the manipulator crashes to the object. To evaluate the avoidance ability of the intermediate link, we proposed a scalar value of Avoidance Manipulability Shape Index(AMSI), which is independent of the obstacle's shape. On the other hand, the danger to crash to the obstacle is depending on the shape of the obstacle, which could be evaluated by the potential field set around the obstacle. This paper proposes control method of the manipulator's shape based on the AMSI to simultaneously avoid obstacles and keep the avoidance ability high with potential.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.523-528
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• 2000

In this paper, the new type biped walking robot which is composed of the minimum number or links just for walking and its appropriate gaits are proposed. The proposed new gaits for this robot are four-crossing, crawling, standing and turning gait. In designing the biped robot we propose the Performance Index which means the needed torque per a moving distance and generate foot trajectories by $3^{rd}$ order spline Interpolation. Among those, numerically we find the optimal conditions which minimize the Performance Index. Dynamically stable walking of the biped robot is realized by satisfying the stability condition of ZMP(zero moment point), which is related to maintaining the ZMP within the region of the supporting foot during the s1n91e leg support phase. We determine the region of mass center from the stability condition of ZMP and plan references which track the mass conte. trajectory of constant velocity. Finally we implement the gaits statically tracking the planned trajectories using PD control method.